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Topic Title: Manx Service Requirements
Topic Summary: One for Mr Alan Capon
Created On: 22 January 2013 06:41 PM
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 22 January 2013 06:41 PM
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WiredScience

Posts: 87
Joined: 25 January 2012

Evening,

I spotted this document on another discussion forum.

MEA Service Requirements

This extract is taken from the above.

Connection tails between the consumer's installation and the meter are supplied by
the consumer. These must be a minimum cross-sectional area of 25mm2 although
larger tails should be provided and may be required dependent on load requirements.
. Test Earth impedance Ze. The MEA will test the earth impedance of the installation
against the following values:-
. Overhead line fed circuit (TT) will require a separate earth to be supplied by
the consumer. The separate earth for this installation must not exceed 200Ω.
The consumer must provide an earth connection with a minimum crosssectional
area of 16mm2 and a suitable test point adjacent to the incoming
service cut-out.



I can accept the requirement for 25mm tails + 16mm earth for all new installations may make sense for operational reasons e.g. can accommodate up to 100A TN-S, or PME without further modification.

But, are they really asking for 16mm all the way to the rod? Or is it 16mm to an accessible earthing terminal (external to any CUs or DBs), then from there an earthing conductor, suitably sized in accordance with the BGB.

I don't come across many TT installs, but I don't remember ever seeing a 16mm MEC in the UK.

Any views or explanations gratefully received.

Wired.
 22 January 2013 07:46 PM
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alancapon

Posts: 5698
Joined: 27 December 2005

The 16mm² is not to the rod. The idea is that it is a future MEC that is ready for a PME or TNS supply. The earth connection to the rod may be taken from the MET, as this will usually be more convenient. If the requirements between the customer installation and the meter box are the same for each supply type and each cutout fuse rating, then it makes it easier for the electrician to install to the company requirements. In the case of a TT supply, it also provides us with a test point adjacent to the meter, where the impedance of the customer's earth may easily be verified as less than 200Ω before the new supply is connected.

Regards,

Alan.
 22 January 2013 09:10 PM
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WiredScience

Posts: 87
Joined: 25 January 2012

Many thanks.
 22 January 2013 09:38 PM
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Avatar for slittle.
slittle

Posts: 3372
Joined: 22 November 2007

Most of our TT's are done with 16mm to the rod. It just gives that extra bit of mechanical strength when the gardener gets excited with the strimmer


Stu
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